Drainage channel of flush toilet

ABSTRACT

Disclosed is a flush toilet drainage channel capable of good flushing. The flush toilet drainage channel includes an ascending channel ( 30 ) which communicates with the downstream side of a toilet bowl ( 10 ) and ascends toward the downstream side. The ascending channel ( 30 ) is formed so that a channel bottom ( 33 ) is gradually rendered wider toward a bottom top ( 32 ) thereof located at the downstream side.

TECHNICAL FIELD

The present invention relates to a drainage channel of a flush toilet.

BACKGROUND ART

Patent Document 1 discloses a conventional drainage channel of a flush toilet. The disclosed drainage channel includes an ascending channel communicating with a downstream side of a toilet bowl and ascending toward the downstream side and a descending channel communicating with the ascending channel and descending toward the downstream side. The ascending channel has a top located at the downstream side and including a horizontal surface extending in a direction perpendicular to a drainage direction of flushing water. The top of the ascending channel has a width that is as large as or larger than the other part of the ascending channel. Accordingly, the drainage channel can increase an amount of flushing water flowing over the top with increase in a water level.

This drainage channel further includes a ledge comprising an inclined surface directed inwardly upward and located in a boundary between the descending channel and a bottom top located at the downstream side of a channel bottom of the ascending channel. Accordingly, a large amount of flushing water having flowed at an initial stage of toilet flushing flows downward into the descending channel so as to be peeled from an inner periphery of the descending channel by the ledge. The flushing water collides against the rear inner periphery of the descending channel opposed to the ledge, whereupon a water screen can be formed in the descending channel. Consequently, a siphon action is caused in a drainage channel of the flush toilet with the result that toilet flushing can be executed.

Furthermore, Patent Document 2 discloses another conventional drainage channel of a flush toilet. The disclosed drainage channel includes an ascending channel communicating with a downstream side of a toilet bowl and ascending toward the downstream side and a descending channel communicating with the ascending channel and descending toward the downstream side. The ascending channel has an upstream end that has a smallest flow channel area in the drainage channel. The ascending channel is formed so that a flow passage area is rendered gradually larger toward the downstream side. Accordingly, when a large amount of waste or the like is excreted into the toilet bowl, the waste or the like can be caught by the upstream end of the ascending channel to thereby be prevented from clogging the ascending channel.

PRIOR ART DOCUMENT Patent Documents

Patent Document 1: Japanese Patent Application Publication No. JP-A-H07-324367

Patent Document 2: Japanese Patent Application Publication No. JP-A-H08-232330

SUMMARY OF THE INVENTION Problem to Be Overcome By the Invention

However, the shape of the ascending channel leading to the top is not considered in the drainage channel of Patent Document 1. As a result, even upon occurrence of a siphon action, flushing water would not desirably flow through the ascending channel depending upon the shape of the ascending channel. In this case, there is a possibility that waste or the like cannot be conveyed with water successfully.

Furthermore, when a flow rate of flushing water flowing over the top is low or when a force of the flushing water is small, there is a possibility that the flushing water cannot be delivered to the rear of an inner periphery of the descending channel opposed to the ledge. In this case, since no water screen is formed in the descending channel, the siphon action cannot be caused in the drainage channel, whereupon flushing becomes insufficient in the flush toilet.

Since the upstream end of the ascending channel in the drainage channel of Patent Document 2 has a small flow passage area, flushing water cannot be caused to smoothly flow fast. Furthermore, since the ascending channel has a flow passage area that is gradually increased toward the downstream side, a turbulent flow tends to occur easily and resistance occurs accordingly, whereupon it is difficult to cause waste to smoothly flow with water through the drain channel. Additionally, since the upstream end of the ascending channel has a small flow passage area as described above, the ascending channel has a possibility of being clogged with waste or the like at the upstream end.

The present invention was made in view of the above-described circumstances in the conventional technique and an object thereof is to provide a drainage channel of the flush toilet, which can successfully perform toilet flushing.

Means for Overcoming the Problem

A drainage channel of a flush toilet, according to the present invention, comprises an ascending channel which communicates with a downstream side of a toilet bowl and ascends toward a downstream side of the drainage channel, wherein the ascending channel is formed so that a channel bottom of the ascending channel is gradually rendered wider toward bottom top thereof located at the downstream side of the drainage channel.

The inventors have found that a flow speed of flushing water near the channel bottom of the ascending channel is lower at the upstream side due to changes in the drainage direction of flushing water from a downward direction to an upward direction at the upstream end of the ascending channel, and the flushing water tends to stagnate, and a flow speed of flushing water is higher at the downstream side than at the upstream side. The inventors have also found that a flow speed of flushing water near the upper surface of the ascending channel is higher in the neighborhood of the upstream end but is lower at the downstream side, whereupon the flushing water tends to stagnate.

Accordingly, the bottom of the ascending channel is gradually rendered wider toward the top thereof located at the downstream side of the drainage channel, whereby the flow passage area is increased in the region where the flow speed of flushing water is high so that a larger amount of flushing water flows through the ascending channel. Consequently, since waste or the like is conveyed with the flushing water with high flow speed to the region where the ascending channel has the increased flow passage area, the waste can successfully be conveyed along the ascending channel.

Accordingly, the drainage channel according to the present invention can perform desirable toilet flushing.

The bottom top may have a substantially horizontal surface extending in a direction perpendicular to a drainage direction of flushing water. In this case, a large amount of flushing water flowing to the downstream end of the ascending channel can flow downstream relative to the top at once. This can reliably form a water screen in a water screen forming region by a constricted part or the like, with the result that a siphon action can reliably be caused in the drainage channel. Since the flushing water flows in the drainage channel further swiftly as the result of occurrence of siphon action, waste or the like can successfully be conveyed with the flushing water with high flow speed to the region where the ascending channel has the increased flow passage area, whereupon the waste can successfully be conveyed along the ascending channel.

The ascending channel may include an upstream end, a vertical middle, a first region between the upstream end and the vertical middle and a second region between the middle and an upstream side of the bottom top, and the ascending channel has a cross-sectional shape in a direction perpendicular to the drainage direction of the flushing water. In the cross-sectional shape of the ascending channel, the first region includes a first upper region and first lower region both relative to the vertical middle, and the first upper region has a larger flow passage area than the first lower region. In the cross-sectional shape of the ascending channel, the second region includes a second upper region and a second lower region both relative to the vertical middle, and the second lower region has a larger flow passage area than the second upper region. In the cross-sectional shape, the ascending channel includes a first upper region and a first lower region both relative to a vertical middle of the first region, the first upper region having a larger flow passage area than the first lower region. In this case, the flow passage area in the upper side where the flushing water has a higher flow speed is increased in the region from the upper end of the ascending channel to the middle part, whereas the flow passage area in the lower side where the flushing water has a higher flow speed is increased in the region from the middle part of the ascending channel to near the upstream side of the top. This can reduce stagnation of flushing water in the ascending channel, so that a large amount of flushing water can successfully flow through an entire region of the ascending channel. Consequently, waste or the like can successively be conveyed in the ascending channel.

The channel bottom of the ascending channel may have a substantially flat surface extending in a/the drainage direction of the flushing water and in a direction perpendicular to the drainage direction. In this case, since the flow passage area near the bottom of the ascending channel can be increased, a larger amount of flushing water can flow in the region where the flow speed of the flushing water is high. Furthermore, the channel bottom of the ascending channel is formed so as to be continuous to the bottom top that extends perpendicular to the drainage direction of the flushing water and has the substantially horizontal surface. Accordingly, the flushing water can flow smoothly in the ascending channel. Consequently, the waste or the like in the ascending channel can successfully be conveyed.

The ascending channel may have a vertical maximum length that is enlarged from the upstream end toward the downstream side in a/the cross-sectional shape of the ascending channel in the direction perpendicular to the drainage direction of the flushing water. In this case, the vertical length in the cross-sectional shape can be increased at the downstream side of the ascending channel. This can prevent the waste or like from being caught on the upper surface of the ascending channel when the waste or the like passes through the bottom top of the downstream end of the ascending channel. Consequently, the waste or the like can be prevented from remaining in the drainage channel to thereby be conveyed successfully.

The drainage channel may further comprise a descending channel communicating with a downstream side of the ascending channel and descending toward the downstream side of the drainage channel, the descending channel having a ledge extending from the bottom top of the ascending channel to inwardly protrude along an inner periphery of the descending channel. In this case, since the ledge is formed so as to protrude inward along the inner periphery of the descending channel, the flushing water having flowed over the bottom top of the ascending channel further flows along the ledge, whereby the flushing water can be supplied into the rear of descending channel. The flushing water having flowed downward from the ledge collides against a constricted part formed lower than the ledge to splash around, thereby forming a water screen in the water screen forming region. Consequently, a siphon action can early be caused in the drainage channel. More specifically, the siphon action can early be caused even by the use of a smaller amount of flushing water.

The invention also provides a drainage channel of a flush toilet, comprising an ascending channel which communicates with a downstream side of a toilet bowl and ascends toward a downstream side of the drainage channel, wherein the ascending channel has a cross-sectional shape in a direction perpendicular to the drainage direction of the flushing water. In the cross-sectional shape, the ascending has a vertical maximum length that is increased from the upstream end toward the downstream side, and the upstream end has an inner surface having a larger crosswise dimension than a longitudinal dimension.

In this drainage channel, part of the flushing water flowing at the lower side of the ascending channel at a lower flow speed is reduced by reducing the longitudinal dimension of the inner surface of the upstream end of the ascending channel. An amount of flushing water flowing at the upper side at a higher speed is increased by increasing the crosswise dimension of the upstream end of the ascending channel. This can increase the flow speed of the flushing water flowing through the upstream end of the ascending channel, whereupon waste or the like can be caused to successfully flow into the drainage channel and can smoothly be discharged. Furthermore, waste or the like can be prevented from clogging the ascending channel since the vertical maximum length of the ascending channel is increased from the upstream end toward the downstream side.

Accordingly, the drainage channel according to the present invention can perform desirable toilet flushing.

The ascending channel may have an upper surface formed into an angled shape such that the upper surface is gradually enlarged from a middle part thereof toward right and left lower parts thereof, in a/the cross-sectional shape of the ascending channel in the direction perpendicular to the drainage direction of the flushing water. In this case, when the region where the flow speed of the flushing water is decreased near the upper surface of the ascending channel is formed into the angled shape, the flow passage area of the region is rendered smaller such that the flow speed of the flushing water is increased, whereupon the flushing water can be prevented from stagnation. Consequently, the flushing water can be caused to successfully flow through the ascending channel and accordingly, waste or the like can be conveyed successfully.

The channel bottom of the ascending channel may have rising surfaces rising from right and left ends thereof, and the rising surfaces have maximum heights near an upstream side of the bottom top located at the downstream side of the drainage channel, respectively, in the cross-sectional shape perpendicular to the drainage direction of the flushing water. In this case, since the heights of the rising surfaces become a maximum near the upstream side of the bottom top of the ascending channel, the flow passage area of this part is increased with the result that the flow of flushing water is rendered smoother. Consequently, the vicinity of the upstream side of the bottom top of the ascending channel can be prevented from being clogged with the waste or the like.

The upper surface of the ascending channel may be formed into an inclined surface extending from a middle part thereof rightward downward and leftward downward and inwardly swollen, in the cross-sectional shape perpendicular to the drainage direction of the flushing water. In this case, the flushing water tends to stagnate in a region near the upper surface. When the region is composed of an inclined surface that is inwardly swollen, the flow speed of the flushing water flowing in the region is increased such that the flushing water can be prevented from stagnation. Consequently, the flushing water can flow through the ascending channel successfully and the waste or the like can desirably be conveyed through the ascending channel.

The ascending channel may have corners between the channel bottom and the rising surfaces rising from the right and left ends of the channel bottom near the upstream end of the ascending channel respectively. The corners may be formed into respective rounded surfaces. The rounded surface of one of the right and left corners may have a larger curvature than the rounded surface of the other corner. A spiral flow resulting from one formed in the toilet bowl flows in the ascending channel in the vicinity of the upstream end thereof. In this case, the flushing water smoothly flows in along the corner with the rounded surface having a smaller curvature. On the other hand, the spiral flow collides against the rising surfaces connected by the corner with the rounded surface having a larger curvature, whereby the flushing water flows downstream of the ascending channel. Thus, the flow of flushing water can be changed to the drainage direction at the upstream end of the ascending channel, whereupon the flow of flushing water can be rendered smoother. Consequently, the drainage channel of the flush toilet can successfully convey the waste or the like.

The drainage channel may further comprise a pipe-like introduction passage downwardly inclined from a lower end of the toilet bowl toward the upstream end of the ascending channel. In this case, the introduction passage rectifies the flushing water inflowing with spiral movement along the toilet bowl surface into a flow along the ascending channel. Consequently, the flushing water can smoothly flow through the ascending channel and the waste or the like can successfully be conveyed.

The invention further provides a drainage channel of a flush toilet, comprising a descending channel which communicates with a downstream side of an ascending channel communicating with a downstream side of a toilet bowl and ascending toward a downstream side of the drainage channel, the descending channel descending toward the downstream side, wherein the descending channel has a ledge which is formed so as to inwardly protrude along an inner periphery of the descending channel.

Since the ledge is formed along the inner periphery of the descending channel so as to inwardly protrude, the flushing water flows along the ledge to thereby be transferred to rearward of the descending channel. The flushing water having flowed downward from the ledge collides against a constricted part formed downward relative to the ledge to thereby splash, forming a water screen in a water screen forming region. Consequently, a siphon action can early be caused in the drainage channel. More specifically, the siphon action can be caused early even when an amount of flushing water is smaller, and waste or the like can be conveyed successfully.

Accordingly, the drainage channel according to the present invention can perform desirable toilet flushing.

The ledge may descend rearward along the inner periphery of the descending channel. In this case, the flushing water can flow as far as to the rear of the descending channel along the inner periphery of the descending channel even when an amount of flushing water flowing along the ledge is small. Consequently, the flushing water flowing downward from the inner periphery of the descending channel can reliably form a water screen even when its amount is smaller. More specifically, the siphon action can be caused early even when an amount of flushing water is smaller, and waste or the like can be conveyed successfully.

The ledge may be formed into an inclined surface directed inwardly upward. In this case, although the provision of the ledge reduces the flow passage area of the descending channel, the change in the reduction of the flow passage area can be slowed down. This can prevent the clogging with the waste or the like due to the ledge and realize successful execution of conveyance of waste or the like.

The descending channel may have a rear surface and the ledge may extend near a middle part of the rear surface of the descending channel. In this case, the flushing water can reliably be sent along the inner periphery of the descending channel to the middle rear surface of the descending channel. Consequently, the flushing water flowing downward from the inner periphery of the descending channel can reliably form a water screen even when its amount is smaller. In particular, when the drainage channel has a lateral channel which communicates with a downstream end of the descending channel and extends laterally, a water screen is formed so as to spread from a lower end of the rear surface of the descending channel, whereupon a siphon action is caused in the drainage channel. Consequently, the water screen can reliably be formed and the siphon action can be caused in the drainage channel by sending the flushing water to the middle rear surface of the descending channel.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a cross-sectional view of the flush toilet of embodiment 1;

FIG. 2 is a plan view of the flush toilet;

FIG. 3 is a cross-sectional view taken along line A-A in FIG. 1;

FIG. 4 is a cross-sectional view taken along line B-B in FIG. 1;

FIG. 5 is a cross-sectional view taken along line C-C in FIG. 1;

FIGS. 6A, 6B and 6C are a cross-sectional view of an ascending channel in embodiment 1, sectional views taken along lines D-D to H-H in FIG. 6A and a cross-sectional view taken along line I-I in FIG. 6A, respectively;

FIG. 7 is a cross-sectional view taken along line J-J in FIG. 1;

FIG. 8 is a cross-sectional view taken along line K-K in FIG. 1;

FIG. 9 is a cross-sectional view taken along line L-L in FIG. 1;

FIG. 10 is a cross-sectional view taken along line P-P in FIG. 1;

FIG. 11 is a cross-sectional view taken along line Q-Q in FIG. 1;

FIG. 12 is a cross-sectional view taken along line R-R in FIG. 1;

FIG. 13 is a cross-sectional view taken from opposite line R-R in FIG. 1;

FIG. 14 is a cross-sectional view of the flush toilet of embodiment 2;

FIG. 15 is a cross-sectional view taken along line W-W in FIG. 14;

FIG. 16 is a cross-sectional view taken along line X-X in FIG. 14;

FIG. 17 is a cross-sectional view taken along line Y-Y in FIG. 14;

FIG. 18 is a cross-sectional view taken along line Z-Z in FIG. 14;

FIG. 19 is a partial sectional view of the descending channel in another embodiment;

FIG. 20 is a partial sectional view of the descending channel in further another embodiment;

FIG. 21 is a cross-sectional view of the flush toilet of embodiment 3;

FIG. 22 is a plan view of the flush toilet of embodiment 3;

FIG. 23 is a cross-sectional view taken along line A-A in FIG. 21;

FIG. 24 is a cross-sectional view taken along line B-B in FIG. 21;

FIG. 25 is a cross-sectional view taken along line C-C in FIG. 21;

FIG. 26 is a cross-sectional view taken along line D-D in FIG. 21;

FIG. 27 is a cross-sectional view taken along line E-E in FIG. 21;

FIG. 28 is an enlarged sectional view taken along line F-F in FIG. 21;

FIG. 29 is an enlarged sectional view taken along line G-G in FIG. 21;

FIG. 30 is an enlarged sectional view taken along line I-I in FIG. 21;

FIG., 31 is an enlarged sectional view taken along line J-J in FIG. 21;

FIG. 32 is an enlarged sectional view taken along line K-K in FIG. 21;

FIG. 33 is an enlarged sectional view of an ascending channel of the flush toilet of embodiment 4;

FIG. 34 is a cross-sectional view taken along line L-L in FIG. 33;

FIG. 35 is a cross-sectional view taken along line M-M in FIG. 33;

FIG. 36 is a cross-sectional view taken along line N-N in FIG. 33;

FIG. 37 is a cross-sectional view taken along line O-O in FIG. 33; and

FIG. 38 is a cross-sectional view taken along line P-P in FIG. 33.

MODE FOR CARRYING OUT THE INVENTION

Embodiments 1 to 4 which embody flush toilets provided with the drainage channel of flush toilet will be described with reference to the accompanying drawings.

Embodiment 1

The flush toilet of embodiment 1 includes a toilet body 1, a tank body 2 set on a rear top of the toilet body 1, a distribution conduit 3 through which flushing water stored in the tank body 2 is discharged into the toilet body 1 and connecting piping 4 communicating between a drain outlet 40A of the toilet body 1 and an inlet of a drainage conduit (not shown) which is open in a floor of a toilet room in which the toilet body 1 is installed. The connecting piping 4 forms a constricted part 5 against which flushing water having flowed downward from the drain outlet 40A collides to thereby splash. A water screen is formed in a water screen forming region S when the flushing water collides against the constricted part 5 to thereby splash. Consequently, a siphon action can be caused in the drainage channel.

The toilet body 1 includes a toilet bowl 10, an introduction passage 20, an ascending channel 30 and a descending channel 40. A drainage channel of the flush toilet is constituted by the introduction passage 20, the ascending channel 30, the descending channel 40 and the connecting piping 4.

The toilet bowl 10 has an upper inner peripheral edge forming a rim water passage 11. The distribution conduit 3 has an inlet 3A connected to a drain outlet of the tank body 2 and first and second discharge conduits 3B and 3C both of which are distributed from each other below the inlet 3A. Upon execution of toilet flushing, flushing water stored in the tank body 2 is discharged from the first discharge conduit 3B toward the rim water passage 11, and the flushing water is also discharged from the second discharge conduit 3C toward the rear of the toilet bowl 10. The flushing water discharged from the first discharge conduit 3B along the rim water passage 11 flows from the rim water passage 11 downward onto the inner surface of the toilet bowl 10. Furthermore, since an amount of flushing water discharged from the first conduit 3B is larger than from the second conduit 3C, a counter-clockwise swirl flow FL is formed in the toilet bowl 10 as viewed above the toilet bowl 10.

The introduction passage 20 is continuous to a lower end of the toilet bowl 10 and is formed into the shape of a pipe as shown in FIGS. 1 and 3 to 5. The introduction passage 20 is inclined downward from the lower end of the toilet bowl 10 toward the rear of the toilet body 1. More specifically, the introduction passage 20 is downwardly inclined toward the upstream end 31 of the ascending channel 30. The introduction passage 20 has a downstream end that is formed successively to the upstream end 31 of the ascending channel 30. The introduction passage 20 has a cross-sectional shape perpendicular to the drainage direction of the flushing water. In the cross-sectional shape, left lower corners 20L and 31L are formed into rounded surfaces having smaller curvatures and curved more gently than right lower corners 20R and 31R respectively. A right side surface 31C rises linearly.

Flushing water is formed into the counter-clockwise swirl flow FL in the toilet bowl 10, flowing into the introduction passage 20. In this case, the flushing water smoothly flows into the introduction passage 20 since the left lower corners 20L and 31L is the rounded surface having the gentle curve. The flushing water having flowed into the introduction passage 20 further flows through the right lower corners 20R and 31R having the larger curvature and a tight curve, colliding against the linearly rising right side surface 31C to thereby change the flow direction to the downstream of the drainage channel. Thus, the flow of flushing water swirling in the toilet bowl 10 can be changed to the flow toward the downstream of the drainage channel by the introduction passage 20, and the flow of flushing water toward the downstream is accelerated to thereby be rectified.

The upstream end 31 of the ascending channel 30 which is the downstream end of the introduction passage 20 has a horizontally long substantially rectangular cross-sectional shape as shown in FIG. 5. The flushing water with a higher flow speed flows at the upper surface 31T side due to the change in the drainage direction of the flushing water from the downward direction to the upward direction at the upstream end 31 of the ascending channel 30. When the vertical dimension is increased in a cross-sectional shape of a part of the drainage channel near the upstream end 31 of the ascending channel 30, the flow speed of the flushing water at the channel bottom 31B side is reduced, whereupon there is a possibility that the flushing water rectified near the channel bottom 31B side may stagnate. In view of the problem, the vertical dimension of the ascending channel 30 is rendered smaller near the upstream end 31 of the ascending channel 30 so that the rectified flushing water can be prevented from stagnating, and a lateral dimension of the ascending channel 30 is increased so that a predetermined flow rate is ensured. As a result, the upstream end 31 of the ascending channel 30 is formed so as to have a horizontally substantially rectangular cross-sectional shape.

The ascending channel 30 is also formed so that a flow passage area A1 of a region above the vertical middle M is larger than a flow passage area B1 of a region below the vertical middle M at the upstream end 31 of the ascending channel 30. Consequently, the upper side flow passage area A1 in the region where the flow speed of the flushing water is higher is increased, so that a larger amount of flushing water can flow into the ascending channel 30. Furthermore, the flow speed of the flushing water is increased near the channel bottom 31B in the upstream end 31 of the ascending channel 30, so that the stagnation of the rectified flushing water can be reduced. Additionally, as described above, the flow of flushing water in the introduction passage 20 is changed to the downstream direction of the drainage channel by the right side surface 31C rising linearly from the right lower corners 20R and 31R with tight curved surfaces having large curvatures respectively, and the flow of flushing water in the downstream direction is accelerated, whereby the flow of flushing water can be optimized.

The ascending channel 30 rises from the upstream end 31 toward the rear of the toilet body 1 (the downstream side). The ascending channel 30 is defined by being surrounded by a channel bottom 33, right and left side surfaces 34R and 34L rising from right and left ends of the channel bottom 33 and an upper surface 35 connecting between upper ends of the right and left side surfaces 34R and 34L, as shown in FIGS. 1, 6A to 6C and 7.

The ascending channel 30 has a cross-sectional shape perpendicular to a drainage direction of flushing water, in which cross-sectional shape a maximum vertical length is enlarged from the upstream end 31 toward the downstream side (from the upstream end 31 to the section taken along line D-D in FIG. 6A). Consequently, the vertical length in the cross-sectional shape can be increased at the downstream side of the ascending channel 30. This can prevent waste or the like from being caught on the upper surface 35 of the ascending channel 30 when the waste or the like passes by a bottom top 32 of the downstream end of the ascending channel 30. Accordingly, the waste or the like can successfully be conveyed without remaining in the drainage channel.

The ascending channel 30 is formed so that the channel bottom 33 thereof is gradually widened toward the bottom top 32 located downstream of the channel bottom 33. The channel bottom 33 is formed into a flat surface extending in the drainage direction of the flushing water and in a direction perpendicular to the drainage direction. The bottom top 32 of the channel bottom 33 has a substantially horizontal surface extending perpendicularly to the drainage direction of the flushing water.

The flushing water near the channel bottom 33 of the ascending channel 30 has a higher flow speed at the downstream side than at the upstream side. Accordingly, a flow passage area of the region where the flow speed of the flushing water is higher is increased by gradually widening the channel bottom 33 of the ascending channel 30 toward the bottom top 32 located downstream of the channel bottom 33, so that a larger amount of flushing water flows through the ascending channel 30. Furthermore, since the channel bottom 33 is formed so as to be continuous to the bottom top 32, the flushing water can smoothly flow in the ascending channel 30. Consequently, the waste or the like can successfully be conveyed through the ascending channel 30.

Furthermore, since the bottom top 32 has the substantially horizontal surface extending perpendicularly to the drainage direction of flushing water, a large amount of flushing water flowing into the downstream end of the ascending channel 30 can flow into the descending channel 40 at the downstream side of the bottom top 32 at once. The flushing water having flowed through the descending channel 40 collides against the constricted part 5 of the connecting piping 4 to splash, thereby forming a water screen in the water screen forming region S with the result that a siphon action can reliably be caused in the drainage channel. Since the occurrence of siphon action results in further vigorous flow of flushing water through the drainage channel, the waste or the like is conveyed together with the vigorous flushing water into the region of the ascending channel 30 where the flow passage area is increased. Consequently, the waste or the like can successfully be conveyed through the ascending channel 30.

Accordingly, the drainage channel of the flush toilet according to embodiment 1 can desirably perform toilet flushing.

The upper surface 31T at the upstream end 31 is formed into an upwardly swollen curved surface in the cross-sectional shape of the ascending channel 30 perpendicular to the drainage direction of flushing water. A part of the upper surface 35 located at the downstream side of the upstream end 31 is formed into an angled shape such that the upper surface 35 is gradually enlarged from a middle part thereof toward rightward downward and leftward downward. Consequently, since the flow passage area is rendered smaller in a region where the flow speed of the flushing water is decreased near the upper surface 35 of the ascending channel 30, the flow speed of the flushing water is increased such that the rectified flushing water can be prevented from stagnation. Consequently, the flushing water in the ascending channel 30 can flow successfully and the waste or the like can be conveyed successfully.

Furthermore, the upper surface 35 is formed into an inclined surface extending from a middle part thereof rightward downward and leftward downward and inwardly swollen, at the upstream end 31 side of the upper surface 35 formed into the angled shape. The flushing water tends to stagnate in a region near the upper surface 35 since the flushing water flows near the downstream side of the upstream end 31 immediately after the direction of flushing water has been changed from the downward direction to the upward direction. Accordingly, when the part of the upper surface 35 where the flushing water tends to stagnate is formed into the inclined surface swollen inward, the flow speed of the flushing water can be further increased and the rectified flushing water can be prevented from stagnating. Consequently, the flushing water can flow in the ascending channel 30 successfully and the waste or the like can be conveyed in the ascending channel successfully.

At the upstream end 31, the ascending channel 30 has an upper region and a lower region relative to the vertical middle M in the cross-sectional shape thereof in the direction perpendicular to the drainage direction of the flushing water. The upper region has a flow passage area A1 and the lower region has a flow passage area B1. The ascending channel 30 is formed so that the flow passage area A1 of the upper region is larger than the flow passage area B1 of the lower region. More specifically, since the flow speed of the flushing water is higher near the upper surface 31T side at the upstream end 31 of the ascending channel 30, the flow passage area A1 at the upper region is rendered larger so that a larger amount of flushing water flows through the upper region. The flow speed of the flushing water near the upper surface 35 becomes lower as the flushing water flows downstream from the upstream end 31. Accordingly, in the cross-sectional shape of the ascending channel 30 in the direction perpendicular to the drainage direction of the flushing water, the flow passage area of the upper region relative to the vertical middle M is gradually rendered small, whereas the flow passage area of the lower region relative to the vertical middle M is accordingly rendered large. The ascending channel 30 is formed so that the upper region has a larger flow passage area than the lower region in a region between the upstream end 31 and an intermediate part 30M. In a region between the intermediate part 30M and the downstream end, the ascending channel 30 is formed so that a flow passage area B2 of a lower region relative to the vertical middle M is larger than a flow passage area A2 of an upper region in the cross-sectional shape of the ascending channel 30 in the direction perpendicular to the drainage direction of the flushing water, as shown in FIGS. 6B and 7.

Thus, the flow passage area at the upper region where the flow speed of the flushing water is higher is rendered larger in the region between the upstream end 31 of the ascending channel 30 and the intermediate part 30M, and the flow passage area at the lower region where the flow speed of the flushing water is higher is rendered larger in the region between the intermediate part 30M and the downstream end. This can reduce stagnation of the rectified flushing water in the ascending channel 30 and realize successful flow of a large amount of flushing water in the entire region of the ascending channel 30. Consequently, the waste or the like can successfully be conveyed through the ascending channel 30.

The descending channel 40 is formed continuously to the downstream side of the ascending channel 30 as shown in FIGS. 1 and 8 to 13. The descending channel 40 extends vertically downward, that is, descends toward the downstream side. The descending channel 40 has a lower end formed with a drain outlet 40A. The connecting piping 4 is connected to the lower end of the descending channel 40. The drain outlet 40A is inserted into a connecting port at the upstream side of the connecting piping 4 to thereby be capable of communicating via the connecting piping 4 with an inlet of a drain pipe which is open in the floor face of a toilet room.

The descending channel 40 has a ledge 41 comprising an inclined surface which is formed so as to extend from the bottom top 32 of the ascending channel 30 and protrude inward along an inner periphery of the descending channel 40 and so as to be directed inwardly upward. Since the ledge 41 protrudes inward along the inner periphery of the descending channel 40, the flushing water having flowed over the bottom top 32 flows along the ledge 41 to thereby be delivered to the rear of the descending channel 40. The flushing water having flowed from the ledge 41 down into the descending channel 40 collides against the constricted part 5 formed on the connecting piping 4, splashing. As a result, a water screen is formed in a water screen forming region S such that a siphon action can early be caused in the drainage channel. In other words, even a small amount of flushing water can cause the siphon action at an early stage of toilet flushing, and the waste or the like can successfully be conveyed with the flush water.

Accordingly, the drainage channel of the flush toilet according to embodiment 1 can perform desirable toilet flushing.

Furthermore, the provision of the ledge 41 reduces the flow passage area of the descending channel 40. However, since the ledge 41 comprises the inclined surface directed inwardly upward, the change in the flow passage area can be rendered gradual. Accordingly, the drainage channel can be prevented from being clogged with waste or the like caught by the ledge 41, whereupon the waste or the like can successfully be conveyed.

The ledge 41 descends rearward from the bottom top 32 of the ascending channel 30 along the inner periphery of the descending channel 40. Accordingly, the flushing water can be delivered along the inner periphery of the descending channel 40 to the rear of the descending channel 40 even when an amount of flushing water flowing from the bottom top 32 to the ledge 41 is smaller. In other words, even when an amount of flushing water is smaller, the flushing Water flows downward from the periphery of the descending channel 40, whereupon a water screen can reliably be formed in the water screen forming region S. Consequently, even a smaller amount of flushing water can cause the siphon action early, so that the waste or the like can successfully be conveyed with the flush water.

The width of the ledge 41 is gradually reduced toward the rear along the inner periphery of the descending channel 40. The ledge 41 acts as a resistance when the siphon action is caused and the waste or the like flows through the descending channel with the flushing water. Accordingly, when the width of the ledge 41 is gradually reduced toward the rear, the siphon action can be caused early and the resistance against the flushing water and the like can be reduced, whereupon the waste or the like can successfully be conveyed.

Embodiment 2

A flush toilet of embodiment 2 has a lateral channel 146 which communicates with a downstream end of the descending channel 140 of the toilet drainage channel and extends laterally toward the rear of the toilet body 101, as shown in FIG. 14. The flush toilet also has a reinforcement wall 150. The descending. channel 140 includes a rear surface 144, and the reinforcement wall 150 extends vertically on a middle part of an outer periphery of the rear surface 144 to thereby reinforce the rear of the toilet body 101. The other construction of the flush toilet of embodiment 2 is substantially the same as that of the flush toilet of embodiment 1. Identical or similar parts in embodiment 2 is labeled by the same reference symbols as those in embodiment 1 and the detailed description of these parts will be eliminated.

The lateral channel 146 is formed in continuity with the downstream end of the descending channel 140. The lateral channel 146 has a downstream end formed with the drain outlet 140A that is open to the rear of toilet body 101. The drain outlet 140A is inserted into an upstream side connection of the connecting member 5 to thereby be capable of communicating with the inlet of the drain pipe which is drawn via the connecting member 5 from the wall of the toilet room.

The descending channel 140 is defined by being surrounded by a front surface 142 extending downward from the bottom top 32 of the ascending channel 30, right and left side surfaces 143R and 143L extending rearward from right and left ends of the front surface 142, a rear surface 144 connecting between rear ends of the right and left side surfaces 143R and 143L, as shown in FIG. 15. The descending channel 140 is formed integrally with the toilet bowl 10, the introduction passage 20, the ascending channel 30 and the like, constituting the toilet body 101. The toilet body 101 is made from ceramic and manufactured by a slip casting method. Accordingly, a recess 144A is formed in the inner periphery of a part etc. on which the reinforcement wall 150 extends from the outer periphery of the rear surface 144. The recess 144A results from the dying of slurry causing shrinkage of the toilet body 101 in the manufacturing process.

The descending channel 140 has the ledge 141 comprising an inclined surface which is formed so as to extend from the bottom top 32 of the ascending channel 30 and protrude inward along an inner periphery of the descending channel 140 and so as to be directed inwardly upward, as shown in FIGS. 14 to 18. Since the ledge 141 protrudes inward along the inner periphery of the descending channel 140, the flushing water having flowed over the bottom top 32 flows along the ledge 141 to thereby be delivered to the rear of the descending channel 140. The flushing water having flowed from the ledge 141 down into the descending channel 140 forms a water screen in the water screen forming region S that is a boundary between the descending channel 140 and the lateral channel 146. As a result, a siphon action can early be caused in the drainage channel. In other words, even a small amount of flushing water can cause the siphon action early, and the waste or the like can successfully be conveyed with the flush water.

Accordingly, the drainage channel of the flush toilet according to embodiment 2 can also perform desirable toilet flushing.

Furthermore, the provision of the ledge 141 reduces the flow passage area of the descending channel 140. However, since the ledge 141 comprises the inclined surface directed inwardly upward, the change in the flow passage area can be rendered gradual. Accordingly, the drainage channel can be prevented from being clogged with waste or the like caught by the ledge 141, whereupon the waste or the like can successfully be conveyed.

The ledge 141 descends rearward from the bottom top 32 of the ascending channel 30 along the inner periphery of the descending channel 140. Accordingly, the flushing water can be delivered along the inner periphery of the descending channel 140 to the rear of the descending channel 140 even when an amount of flushing water flowing from the bottom top 32 to the ledge 141 is smaller. In other words, even when an amount of flushing water is smaller, the flushing water flows downward from the periphery of the descending channel 140, whereupon a water screen can reliably be formed in the water screen forming region S. Consequently, even a smaller amount of flushing water can cause the siphon action early, so that the waste or the like can successfully be conveyed with the flush water.

The width of the ledge 141 is gradually reduced toward the rear along the inner periphery of the descending channel 140. The ledge 141 acts as a resistance when the siphon action is caused and the waste or the like flows through the descending channel 140 with the flushing water. Accordingly, when the width of the ledge 141 is gradually reduced toward the rear, the siphon action can be caused early and the resistance against the flushing water and the like can be reduced, whereupon the waste or the like can successfully be conveyed.

Additionally, the ledge 141 extends to the middle part of the rear surface 144 of the descending channel 140, with the result that the flushing water can reliably be delivered along the inner periphery of the descending channel 140 to the middle part of the rear surface 144. As a result, the water screen is formed so as to be spread from the lower end of the rear surface 144, whereby the siphon action can be caused in the drainage channel. In particular, the flushing water can be delivered to the recess 144A formed in the middle of the rear surface 144. This can reliably prevent the failure that no water screen is formed around the recess 144A such that no siphon action is caused in the drainage channel. Consequently, the siphon action can reliably be caused in the drainage channel, so that the waste or the like can successfully be conveyed with the flush water.

Embodiment 3

The flush toilet of embodiment 3, as shown in FIGS. 21 and 22, includes a toilet body 51, a tank body 52 set on a rear top of the toilet body 51, a distribution conduit 53 through which flushing water stored in the tank body 52 is discharged into the toilet body 51 and connecting piping 54 communicating between a drain outlet 90A of the toilet body 51 and an inlet of a drainage conduit (not shown) which is open in a floor of a toilet room in which the toilet body 51 is installed. The toilet body 51 includes a toilet bowl 60, an introduction passage 70, an ascending channel 80 and a descending channel 90. A drainage channel of the flush toilet is constituted by the introduction passage 70, the ascending channel 80, the descending channel 90 and the connecting piping 54.

The connecting piping 54 includes a first constricted part 55A formed beneath the drain outlet 90A and a second constricted part 55B formed in a lower portion thereof. The flushing water collides against the first and second constricted parts 55A and 55B to thereby splash, forming a water screen near the constricted parts 55A and 55B. Consequently, a siphon action can be caused in the drainage channel.

The toilet bowl 60 has a first bowl surface 61, a second bowl surface 62 having a, larger inclination than the first bowl surface and extending downward in continuity with the first bowl surface 61, and a third bowl surface 63 extending above a rear part of the second bowl surface 62 and curved upward.

The toilet bowl 60 has an upper inner peripheral edge forming a rim water passage 64. The distribution conduit 53 has an inlet 53A connected to a drain outlet of the tank body 52 and first and second discharge conduits 53B and 53C both of which are distributed from each other below the inlet 53A. Upon execution of toilet flushing, flushing water stored in the tank body 52 is discharged from the first discharge conduit 53B toward the rim water passage 64, and the flushing water is also discharged from the second discharge conduit 53C toward the rear of the toilet bowl 60.

The flushing water discharged from the first discharge conduit 53B along the rim water passage 64 flows from the rim water passage 64 downward onto the first and second bowl surfaces 61 and 62. Accordingly, a counter-clockwise horizontal swirl flow is formed in the toilet bowl 60 as viewed above the toilet bowl 60.

Furthermore, the flushing water discharged from the second discharge conduit 53C flows downward along the third bowl surface 63, flowing directly into the introduction passage 70. Accordingly, the force of the horizontal swirl flow in the toilet bowl 60 can be reduced at the rear of the toilet bowl 60 and can be changed into a swirl flow on a plane substantially perpendicular to the drainage direction of the introduction passage 70. Consequently, since waste or the like can be collected to the middle of the introduction passage 70 without being spread, the waste or the like can smoothly be discharged.

The first bowl surface 61 is formed into a downwardly recessed curved recess 61A in the front widthwise middle thereof on a planar view, as shown in FIGS. 23 and 24. Furthermore, the recess 61A has both widthwise ends formed with upwardly protruding curved convex portions 61B respectively on the planar view. The convex portion 61B is formed into a curved surface having a smaller curvature than the recess 61A.

The recess 61A gradually descends toward the rear side of the toilet bowl 60 and can desirably prevent urine from splashing on the first bowl surface 61. The flushing water having flowed downward from the rim water passage 64 onto the first bowl surface 61 of the toilet bowl 60 further flows along the recess 61A to the second bowl surface 62 side at an early stage of toilet flushing.

The second bowl surface 62 is formed into a convex shape in which the entire periphery thereof is downwardly vertical or swollen to the sealing water surface W side, as shown in FIGS. 21 and 25 to 27. More specifically, the second bowl surface 62 rises from the outer periphery of the sealing water surface W such that the flushing water swirling on the first bowl surface 61 can early flow downward along the second bowl surface 62 to thereby flow into the introduction passage 70. Accordingly, the waste or the like can be collected into the introduction passage 70 by the second bowl surface 62 without being spread. The second bowl surface 62 has an entire upper periphery formed into a curved portion R with a curved convex shape. The third bowl surface 63 is formed into a part of the curved portion R in the rear part of the toilet bowl 60.

The toilet bowl 60 has a rear in which the curved portion R is formed into a curved surface with a smaller curvature. Accordingly, the flushing water is easy to flow downward toward the introduction passage 70. On the other hand, the toilet bowl 60 has a front in which the curved portion R is formed into a curved surface with a larger curvature. Accordingly, since the second bowl surface 62 is formed into the vertical shape, the flushing water flowing downward into the second bowl surface 62 to thereby swirl can be prevented from re-spreading outward above the second bowl surface 62, whereupon the flushing water can be directed to the introduction passage 70 early.

The sealing water surface W has a substantially elliptic shape long in the front-back direction as viewed in a planar view, as shown in FIG. 22. The sealing water surface W includes a front side W1 having a largest curvature as viewed in the planar view. As a result, the flushing water is caused to flush back on the front right and left side portions of the second bowl surface 62 to thereby be directed to the introduction passage 70. Furthermore, the sealing water surface W has a point P in front of the middle in the front-back direction, and the width thereof is a maximum at the point P as viewed in the planar view. The flushing water flowing downward from the first bowl surface 61 along the second bowl surface 62 onto the sealing water surface W is caused to splash on the front side portion with a larger curvature, with the result that the flow speed of the flushing water is increased in the rear of the point P as the flushing water comes near the introduction passage 70. Accordingly, since the waste or the like rapidly flows into the introduction passage 70, the waste or like can be collected into the upstream end 81 of the ascending channel 80 of the drainage channel, and the siphon action can be caused early.

The introduction passage 70 is continuous to the lower end of the toilet bowl 60 and is formed into a tubular shape. The introduction passage 70 is inclined downward from the lower end of the toilet bowl 60 toward the rear of the toilet body 51. More specifically, the introduction passage 70 is inclined downward toward the upstream end 81 of the ascending channel 80. The introduction passage 70 has a downstream end formed in continuity with the upstream end 81 of the ascending channel 80. When flowing along the inner periphery of the introduction passage 70, the flushing water is constricted by the introduction passages 70 to thereby be rectified, so that the flow of the flushing water is rendered smooth.

The introduction passage 70 includes a channel bottom 70B and corners 70E and 70D between the channel bottom 70B and right and left sides 70C formed on the right and left sides of the channel bottom 70B respectively, as shown in FIG. 27. The corners 70D and 70E are formed so as to have respective curved surfaces. The left corner 70D has a smaller curvature than the right corner 70E, as viewed from the front of the toilet body 51. In other words, the left corner 70D has a gentler curved surface than the right corner 70E.

The flushing water formed into the counter-clockwise horizontal swirl flow by the toilet bowl 60 is changed by the flushing water flowing downward on the third bowl surface 63 into a swirl flow swirling on a plane substantially perpendicular to the drainage direction of the introduction passage thereby flowing into the introduction passage 70. In this case, since the left corner 70D has a gentler curve, the flushing water smoothly flows into the introduction passage 70. The flushing water having flowed into the introduction passage 70 collides against the right side 70C rising linearly from the right lower corner 70E with a tight curved surface having a large curvature to thereby change the direction of flow into the downstream direction of the introduction passage 70. Consequently, the flushing water swirled by the toilet bowl 60 can be changed by the introduction passage 70 into the flow directed to the ascending channel 80 of the toilet drainage channel to thereby be rectified.

The ascending channel 80 of the toilet drainage channel has the upstream end 81 having an upper surface 81A and a channel bottom 81B both formed into a substantially horizontal shapes respectively, as shown in FIG. 28. The upper surface 81A has right and left corners both of which are angular. The channel bottom 81B has right and left corners 81E and 81D both of which are rounded, and the upstream end 81 is formed into a generally cup-shape as a whole. The left corner 81D has a smaller curvature than the right corner 81E. More specifically, the left corner 81D has a gentler curved surface than the right corner 81E.

The upstream end 81 of the ascending channel 80 has an opening having a crosswise dimension larger than a lengthwise dimension, and the lengthwise dimension X is 50 mm and the crosswise dimension Y is 77 mm. Thus, the flushing water and floating waste or the like can be rendered easier to flow into the ascending channel 80 by setting the crosswise dimension larger than the lengthwise dimension, whereupon the siphon action can be caused early.

More specifically, the flow speed of the flushing water is reduced at a lower part in the upstream end 81 of the ascending channel 80 since the flushing water creeps into the lower side of the upstream end 81, with the result of occurrence of stagnation. Accordingly, when the lengthwise dimension of the upstream end 81 is reduced and the crosswise dimension thereof is increased, the flow passage area of the upper part where the flushing water flows faster is increased, whereupon the flushing water can smoothly flow into the upstream end 81 of the ascending channel 80 and accordingly be rectified. Furthermore, since the crosswise dimension of the upstream end 81 of the ascending channel 80 is larger, this part of the ascending channel 80 can be prevented from being clogged with the waste or the like. Additionally, the flow passage area of the upper part where the flow speed of the flushing water is higher can be increased by rendering the right and left corners of the upper surface angular.

The flushing water rectified in the introduction passage 70 is also rectified at the upstream end 81 of the ascending channel 80. Accordingly, the flushing water flows into the ascending channel 80 in the rectified state. Consequently, the occurrence of turbulent flow can be suppressed even when a lengthwise dimension of the ascending channel 80 is increased, and the waste or the like can be discharged smoothly.

The ascending channel 80 has the lengthwise dimension X of 62 mm and the crosswise dimension Y of 77 mm in a cross-sectional shape in front of the bottom top 82 as shown in FIG. 32. Furthermore, the ascending channel 80 includes the upper surface middle part which forms an upwardly expanded space 80A. Since the space 80A renders the waste easier to turn when the waste gets over the bottom top 82, even hard and/or long waste can be discharged over the bottom top 82 to the descending channel 90 side. In other words, the drainage channel can be prevented from being clogged with waste or the like near the bottom top 82. Consequently, when a siphon action is caused in the drain channel, the waste or the like can successfully be discharged with a smaller amount of flushing water without the clogging of the drainage channel with the waste or the like near the bottom top 82.

The ascending channel 80 has the bottom top 82 formed on the substantially horizontal plane and extending in the direction perpendicular to the drainage direction of the flushing water as shown in FIG. 29. Accordingly, a large amount of flushing water flows downward at a stroke into the descending channel 90 located at the downstream side of the bottom top 82 when the sealing water surface W in the ascending channel 80 is raised. Consequently, the siphon action can be caused early and yet reliably. The bottom top 82 has a crosswise dimension Y that is 77 mm, which value is equal to the crosswise dimension of the upstream end 81 of the ascending channel 80.

The descending channel 90 is formed continuously to the downstream side of the ascending channel 80 as shown in FIGS. 21, 30 and 31. The descending channel 90 is formed into a cylindrical shape and extends vertically downward, that is, descends toward the downstream side. The descending channel 90 has a lower end formed with a drain outlet 90A. The drain outlet 90A side of the descending channel 90 is inserted into an upstream side connecting port of the connecting piping 54 to be connected to the connecting piping 54 by the use of a packing P. The drain outlet 90A communicates with an inlet of a drain pipe which is open in the floor face of a toilet room via the connecting piping 54.

In this flush toilet, part of the flushing water swirls on the toilet bowl 60 to flow downward along the second bowl surface 62, and other part of the flushing water flows downward along the third bowl surface 63. The flushing water flowing through both passages is collected into the introduction passage 70. The sealing water surface W in the ascending channel 80 then rises and the flushing water flows over the bottom top 82 downward into the descending channel 90. The flushing water having been discharged from the drain outlet 90A of the descending channel 90 collides against the constricted portions 55A and 55B formed on the connecting piping 54 to thereby splash. This forms a water screen near the constricted portions 55A and 55B, with the result that the siphon action can early be caused in the drainage channel. More specifically, even a smaller amount of flushing water can early cause the siphon action and accordingly, the waste or the like can successfully be conveyed.

Accordingly, the drainage channel of the flush toilet according to embodiment 3 can also perform desirable toilet flushing.

Embodiment 4

The flush toilet of embodiment 4 differs from embodiment 3 in the configuration of the ascending channel 180 of the toilet drainage channel as shown in FIGS. 33 to 38. Embodiment 4 is the same as embodiment 3 in the other construction. Identical or similar parts in embodiment 4 will be labeled by the same reference symbols as those in embodiment 3 and detailed description of these parts will be eliminated.

The ascending channel 180 has a cross-sectional shape in the direction perpendicular to the drainage direction of the flushing water. In the cross-section shape, the ascending channel 180 includes a channel bottom 183, rising surfaces 185 and 184 rising longitudinally from right and left sides of the channel bottom 183 respectively, and angled upper surfaces 186, 187 and 188 connected to upper ends of the rising surfaces 184 and 185.

The upper surface middle part 186 is located at a middle part perpendicular to the. drainage direction of the flushing water. The inclined surfaces 187 and 188 extending leftward and. rightward from the upper surface middle part 186 so as to be downwardly inclined and so as to extend toward upper ends of the rising surfaces 184 and 185, respectively. The inclined surfaces 187 and 188 are formed, at an upstream side of the ascending channel 180, into respective curved shapes swollen inward (to the ascending channel 180 side) as shown in FIG. 34. The inclined surfaces 187 and 188 is further formed, at the downstream side of the ascending channel 180, into a substantially linear shape, as shown in FIGS. 35 to 37.

Furthermore, the right and left rising surfaces 185 and 184 have respective maximum heights near the upstream side of the bottom top 182 as shown in FIG. 38. The ascending channel 180 also has a maximum flow passage area in this part thereof.

In the ascending channel 180, the flushing water flowing from the upstream side to the downstream side forms a water flow WS with higher flow speed as shown in FIG. 33. More specifically, the upstream end 181 of the ascending channel 180 has a cross-sectional shape in the direction perpendicular to the drainage direction of the flushing water. The flushing water flows into the lower side at the upstream end 181 in the cross-sectional shape of the ascending channel 180, with the result that the flow speed of the flushing water is reduced. Accordingly, the flushing water tends to easily stagnate in the lower side in the cross-sectional shape of the ascending channel 180 in the direction perpendicular to the drainage direction of the flushing water. On the other hand, in the upstream end 181 of the ascending channel 180, a water flow in the upper side in the aforesaid cross-sectional shape flows in the ascending channel 180, maintaining its higher flow speed. The water flow with the higher flow speed flows in the ascending channel 180 toward the bottom top 182.

Accordingly, the flow speed at the channel bottom 183 side is increased in a section from the middle part of the ascending channel 180 to a part before the bottom top 182. As a result, the flow speed is reduced at the side of the upper surfaces 186, 187 and 188, whereby the flushing water tends to easily stagnate. In view of this, the upper surfaces 186 to 188 are formed into the angled shape, and the inclined surfaces 187 and 188 are formed into the curved shapes swollen inside, whereupon the flow speed at the side of the upper surfaces 186 to 188 is maintained so as not to be reduced and accordingly, the flushing water flows smoothly.

Thus, in the ascending channel 180, the flow passage area of the part where the water flow WS with a higher flow speed flows is increased, and the flow passage area of the other part is reduced, whereby the flushing water can flow smoothly without stagnation. More specifically, in the part of the ascending channel 180 from the upstream end 181 to the middle part thereof, the upper side water flow maintains the higher flow speed in the cross-sectional shape of the ascending channel 180 in the direction perpendicular to the drainage direction of the flushing water. Accordingly, the flow passage area at the upper side relative to the middle in the vertical direction is formed so as to be larger than the flow passage area at the lower side. In the part of the ascending channel 180 from the middle part to the vicinity of the upstream side of the bottom top 182, the flow passage area at the lower side relative to the middle in the vertical direction is formed so as to be larger than the flow passage area at the upper side. Furthermore, the channel bottom 183 of the ascending channel 180 is formed into the flat surface extending in the drainage direction of the flushing water and in the direction perpendicular to the drainage direction of the flushing water. Consequently, a large amount of flushing water with the higher flow speed can flow along the channel bottom 183 from the middle part to the bottom top 182 of the ascending channel 180.

The ascending channel 180 is formed so that the heights of the rising surfaces 184 and 185 becomes maximum in the vicinity of the upstream side of the bottom top 182, whereby the flow passage area is increased as shown in FIG. 38. Consequently, since waste or the like tends to easily turn in passing over the bottom top 182 of the ascending channel 180, the ascending channel 180 can be prevented from being clogged with the waste or the like at the bottom top 182. Furthermore, the ascending channel 180 is formed with the angled upper surfaces 186 to 188 located near the upstream side of the bottom top 182. This maintains the flow speed of the flushing water at the side of the upper surfaces 186 to 188 so that the flow speed is prevented from being excessively reduced. Consequently, the ascending channel 180 can also be prevented from being clogged with the waste or the like at the bottom top 182.

Accordingly, the drainage channel of the flush toilet according to embodiment 4 can also perform desirable toilet flushing.

The invention should not be limited to the embodiments 1 to 4 described above with reference to the drawings but, for example, the following embodiments covers the technical scope of the invention.

(1) Although the ascending channel is formed in continuity with the downstream end of the introduction passage in each of embodiments 1 to 4, the ascending channel may be formed independent of the downstream end of the introduction passage and connected to the downstream end.

(2) Although descending channel is formed in continuity with the downstream side of the ascending channel in each of embodiments 1 to 4, the descending channel may be formed independent of the ascending channel and connected to the downstream side of the ascending channel.

(3) Although the flush toilet is configured so that flushing water is stored in the tank body set on the rear upper surface of the toilet body and supplied to the toilet body, in each of embodiments 1 to 4, the flush toilet may not be provided with any tank body and the flush water may directly be supplied via an on-off valve from a water supply source.

(4) In the cross-sectional shape of the ascending channel in the direction perpendicular to the drainage direction of flush water, the relation between the flow passage area ratios of upper and lower regions relative to the vertical middle of the ascending channel are reversed at the middle of the ascending channel in each of embodiments 1, 2 and 4. However, the ratio between the flow passage areas of upper and lower regions may be constant throughout the ascending channel.

(5) Although the channel bottom of the ascending channel is formed into the substantially flat surface in each of embodiments 1, 2 and 4, the channel bottom may not be flat.

(6) Although the bottom top of the ascending channel has the substantially horizontal surface extending perpendicularly to the drainage direction of flushing water in each of embodiments 1 to 4, the bottom top may not be substantially flat.

(7) Although the upper surface of the ascending channel is formed into the angled shape in each of embodiments 1, 2 and 4, the upper surface may not be angled.

(8) Although the ledge is inclined rearwardly downward along the inner periphery of the descending channel in each of embodiments 1 and 2, the ledge may not be inclined downward.

(9) Although the width of the ledge is gradually reduced toward the rear along the inner periphery of the descending channel in each of embodiments 1 and 2, the width of the ledge may not be reduced.

(10) Although the ledge is formed into the inwardly upward inclined surface in each of embodiments 1 and 2, the ledge may be a horizontal surface 241 as shown in FIG. 19 or an outwardly upward inclined surface 341 as shown in FIG. 20.

(11) Although the introduction passage connects between the lower end of the toilet bowl and the upstream end of the ascending channel in each of embodiments 1 to 4, the introduction passage may not be provided and the upstream end of the ascending channel may be connected directly to the lower end of the toilet bowl.

(12) Although the counterclockwise swirl flow is formed in the toilet bowl in each of embodiments 1 to 4, the flushing water may be swirled clockwise. In this case, the introduction passage may be mirror-reversed in shape relative to the shape in each embodiment.

(13) Although the connecting piping is formed with one or two constricted portions in each of embodiments 1, 3 and 4, the descending channel may be provided with one or two constricted portions.

(14) In each of embodiments 1, 2 and 4, the region at the lower side relative to the vertical middle of the ascending channel has a larger flow passage area than the region at the upper side in the cross-sectional shape of the ascending channel in the direction perpendicular to the drainage direction of flushing water in the region from the middle of the ascending channel to the downstream end. However, the flow passage area of the upper side maybe larger than that of the lower side near the upstream end. The reason for this is that the ascending channel is not full of flushing water to the upper surface near the upstream end thereof in many cases with the result that the shape of the upper surface and the flow passage area do not affect the flow of flushing water.

(15) In each of embodiments 1 to 4, the maximum vertical length gradually increased from the upstream end toward the downstream side in the cross-sectional shape of the ascending channel in the direction perpendicular to the drainage direction of flushing water. However, sewage or the like may only be prevented from being caught on the bottom top of the downstream end of the ascending channel, and the cross-sectional shape at a suitable location of the ascending channel may only be enlarged in the vertical length than the downstream end.

(16) Although the introduction passage is formed into the annular shape in each of embodiments 1 to 4, the introduction passage may not be annular. In this case, the bottom surface of the introduction passage may be a descending inclined surface and one of the right and left side corners may be formed so as to have a smaller or larger curvature than the other side corner according to the swirl direction of flushing water.

(17) Although the ascending channel has a substantially cup-shaped upstream end in each of embodiments 3 and 4, the upstream end may not be cup-shaped. In this case, the upstream end has the shape of an ellipse with a larger lateral dimension than a longitudinal dimension in the cross-sectional shape of the upstream end of the ascending channel. Furthermore, a horizontally long rectangular shape of the upstream end of the ascending channel has a larger effect than an elliptic sectional shape, and a substantially cup-shaped sectional shape has a larger effect than the horizontally long rectangular shape.

(18) Although the invention is applied to the flush toilet of the type that a siphon action is caused, in each of embodiments 1 to 4, the invention may be applied to flush toilets of various flush types. The flush toilet may be of the type that a siphon action is not caused.

INDUSTRIAL APPLICABILITY

The present invention is applicable to a flush toilet.

EXPLANATION OF REFERENCE SYMBOLS

10, 60 . . . toilet bowl

20, 70 . . . introduction passage

30, 80, 180 . . . ascending channel

31, 81, 181 . . . upstream end

31R, 31L, 81D, 81E . . . corner

32, 82, 182 . . . bottom top

33, 183 . . . channel bottom

35, 186, 187, 188 . . . upper surface

40, 90 . . . descending channel

41, 141 . . . ledge

144 . . . rear surface

184, 185 . . . rising surface 

1. A drainage channel of a flush toilet, comprising an ascending channel which communicates with a downstream side of a toilet bowl and ascends toward a downstream side of the drainage channel, wherein the ascending channel is formed so that a channel bottom of the ascending channel is gradually rendered wider toward a bottom top thereof located at the downstream side of the drainage channel.
 2. The drainage channel according to claim 1, wherein the bottom top has a substantially horizontal surface extending in a direction perpendicular to a drainage direction of flushing water.
 3. The drainage channel according to claim 1, wherein the ascending channel includes an upstream end, a vertical middle, a first region between the upstream end and the vertical middle and a second region between the middle and an upstream side of the bottom top, and the ascending channel has a cross-sectional shape in a direction perpendicular to the, drainage direction of the flushing water; in the cross-sectional shape of the ascending channel, the first region includes a first upper region and first lower region both relative to the vertical middle, and the first upper region has a larger flow passage area than the first lower region; and in the cross-sectional shape of the ascending channel, the second region includes a second upper region and a second lower region both relative to the vertical middle, and the second lower region has a larger flow passage area than the second upper region.
 4. The drainage channel according to claim 1, wherein the channel bottom of the ascending channel has a substantially flat surface extending in a/the drainage direction of the flushing water and in a direction perpendicular to the drainage direction.
 5. The drainage channel according to claim 1, wherein the ascending channel has a vertical maximum length that is enlarged from the upstream end toward the downstream side in a/the cross-sectional shape of the ascending channel in the direction perpendicular to the drainage direction of the flushing water.
 6. The drainage channel according to claim 5, wherein the ascending channel has an upper surface formed into an angled shape such that the upper surface is gradually enlarged from a middle part thereof toward right and left lower parts thereof in the cross-sectional shape of the ascending channel in the direction perpendicular to the drainage direction of the flushing water.
 7. The drainage channel according to claim 1, further comprising a descending channel communicating with a downstream side of the ascending channel and descending toward the downstream side of the drainage channel, the descending channel having a ledge extending from the bottom top of the ascending, channel to inwardly protrude along an inner periphery of the descending channel.
 8. The drainage channel according to claim 7, wherein the ledge is formed into an inclined surface directed inwardly upward.
 9. The drainage channel according to claim 7, wherein the descending channel has a rear surface and the ledge extends, near a middle part of the rear surface of the descending channel.
 10. The drainage channel according to claim 7, wherein the ledge descends rearward along the inner peripheral surface of the descending channel.
 11. A drainage channel of a flush toilet, comprising an ascending channel which communicates with a downstream side of a toilet bowl and ascends toward a downstream side of the drainage channel, wherein the ascending channel has a cross-sectional shape in a direction perpendicular to the drainage direction of the flushing water; and in the cross-sectional shape, the ascending channel has a vertical maximum length that is increased from the upstream end toward the downstream side and the upstream end has an inner surface having a larger crosswise dimension than a longitudinal dimension.
 12. The, drainage channel according to claim 1, wherein the ascending channel has an upper surface formed into an angled shape such that the upper surface is gradually enlarged from a middle part thereof toward right and left lower parts thereof, in a/the cross-sectional shape of the ascending channel in the direction perpendicular to the drainage direction of the flushing water.
 13. The drainage channel according to claim 12, wherein the channel bottom of the ascending channel has rising surfaces rising from right and left ends thereof, and the rising surfaces have maximum heights near an upstream side of the bottom top located at the downstream side of the drainage channel, respectively, in the cross-sectional shape perpendicular to the drainage direction of the flushing water.
 14. The drainage channel according to claim 12, wherein the upper surface of the ascending channel is formed into an inclined surface extending from a middle part thereof rightward downward and leftward downward and inwardly swollen, in the cross-sectional shape perpendicular to the drainage direction of the flushing water.
 15. The drainage channel according to claim 1, wherein the ascending channel has corners between the channel bottom and the rising surfaces rising from the right and left ends of the channel bottom near the upstream end of the ascending channel respectively; the corners are formed into respective rounded surfaces; and the rounded surface of one of the right and left corners has a larger curvature than the rounded surface of the other corner.
 16. The drainage channel according to claim 1, further comprising a pipe-like introduction passage downwardly inclined from a lower end of the toilet bowl toward the upstream end of the ascending channel.
 17. A drainage channel of a flush toilet, comprising a descending channel which communicates with a downstream side of an ascending channel communicating with a downstream side of a toilet bowl and ascending toward a downstream side of the drainage channel, the descending channel descending toward the downstream side, wherein the descending channel has a ledge which extends from a bottom top located at a downstream side of a channel bottom of the ascending channel and is formed so as to inwardly protrude along an inner periphery of the descending channel.
 18. The drainage channel according to claim 17, wherein the ledge descends rearward along the inner periphery of the descending channel.
 19. The drainage channel according to claim 17, wherein the ledge is formed into an inclined surface directed inwardly upward.
 20. The drainage channel according to claim 17, wherein the descending channel has a rear surface and the ledge extends near a middle part of the rear surface of the descending channel.
 21. The drainage channel according to claim 11, wherein the ascending channel has an upper surface formed into an angled shape such that the upper surface is gradually enlarged from a middle part thereof toward right and left lower parts thereof, in a/the cross-sectional shape of the ascending channel in the direction perpendicular to the drainage direction of the flushing water.
 22. The drainage channel according to claim 11, wherein the ascending channel has corners between the channel bottom and the rising surfaces rising from the right and left ends of the channel bottom near the upstream end of the ascending channel respectively; the corners are formed into respective rounded surfaces; and the rounded surface of one of the right and left corners has a larger curvature than the rounded surface of the other corner.
 23. The drainage channel according to claim 11, further comprising pipe-like introduction passage downwardly inclined from a lower end of the toilet bowl toward the upstream end of the ascending channel. 